Exploring Clang Modules

Given at try! Swift Tokyo 2018

1. Exploring Clang Modules Samuel Giddins 1
2. @segiddins CocoaPods, Bundler, RubyGems Mobile Developer Experience @ Square Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 2
3. Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 3
4. cool_function.h #define AUTHORS_NAME "segiddins" extern void printMyName(char *); main.c #include "cool_function.h" int main(int argc, char **argv) { printMyName(AUTHORS_NAME); } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 4
5. main.c extern void printMyName(char *); int main(int argc, char **argv) { printMyName("segiddins"); } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 5
6. #include "header.h" #define MAGIC_NUMBER 42 ... ... ... #include "header2.h" // also includes header.h preprocessed into: static int secretNumber = -1; static int secretNumber = 42; Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 6
7. // header.h #ifndef __HEADER_H #define __HEADER_H ... #endif // #ifndef __HEADER_H Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 7
8. #import "header.h" Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 8
9. Enter Module Maps Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 9
10. Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 10
11. UsefulFramework.modulemap / module.modulemap framework module UsefulFramework { umbrella header "UsefulFramework.h" export * module * { export * } } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 11
12. UsefulFramework.modulemap framework module UsefulFramework { umbrella header "UsefulFramework.h" export * module * { export * } } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 12
13. UsefulFramework.modulemap framework module UsefulFramework { umbrella header "UsefulFramework.h" export * module * { export * } } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 13
14. UsefulFramework.modulemap framework module UsefulFramework { umbrella header "UsefulFramework.h" export * module * { export * } } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 14
15. UsefulFramework.modulemap framework module UsefulFramework { umbrella header "UsefulFramework.h" export * module * { export * } } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 15
16. main.swift import UsefulFramework main.m @import UsefulFramework; Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 16
17. Module Maps, the hard part Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 17
18. Module Maps, the hard part Lessons from CocoaPods Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 18
19. • Umbrella Directories • Explicit Submodules • Private Headers • Textual Headers • ... • Automatic Module Map Discovery • Relative Paths Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 19
20. Umbrella Directories framework module UsefulFramework { umbrella "HeadersDirectory" } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 20
21. Explicit Submodules Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 21
22. Explicit Submodules framework module UsefulFramework { umbrella header "UsefulFramework.h" explicit module ForSubclassEyesOnly { header "ComplicatedTextField_subclass.h" } } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 22
23. Private Headers framework module UsefulFramework { umbrella header "UsefulFramework.h" private header "PrivateHashMapImpl.h" } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 23
24. Textual Headers framework module UsefulFramework { umbrella header "UsefulFramework.h" textual header "AssertMacros.h" } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 24
25. Requires framework module UsefulFramework { umbrella header "UsefulFramework.h" requires objc_arc, blocks, !altivec } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 25
26. Conflicts framework module UsefulFramework { umbrella header "UsefulFramework.h" conflict PointlessFramework, "we do something more useful than that framework" } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 26
27. Automatic Module Map Discovery $ tree include include !"" baking.h !"" cake.h !"" cookie.h !"" module.modulemap Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 27
28. Relative Paths Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 28
29. Relative Paths framework module UsefulFramework { header "UsefulFramework.h" } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 29
30. Modules & Swift Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 30
31. But my Swift code doesn't have headers... Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 31
32. But my Swift code doesn't have headers... It does ! Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 32
33. swiftc Understands .swiftmodule Files Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 33
34. The Mixed Framework Process 1. Compile all .swift files 2. Generate ModuleName-Swift.h in the (empty) .framework 3. "Extend" existing module map with .Swift submodule 4. Compile .m files Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 34
35. Extended Module Maps module ModuleName.Swift { header "ModuleName-Swift.h" requires objc } Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 35
36. Same-Module Imports Superclass.m #import <ModuleName/ModuleName-Swift.h> Subclass.swift // nothing to import! Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 36
37. Same-Module Imports swiftc Useful.swift -module-name UsefulFramework -import-underlying-module -emit-module -emit-objc-header -Xcc -fmodule-map-file="UsefulFramework.modulemap" Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 37
38. Swift Static Libraries in CocoaPods All of the changes needed: https://github.com/CocoaPods/CocoaPods/pull/6966 Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 38
39. Are Modules the Future? • Tied to headers • Swift module stability • Still confusing • Better than C Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 39
40. Some Resources • Clang Docs https://clang.llvm.org/docs/Modules.html • Clang Source https://github.com/llvm-mirror/clang/blob/master/include/clang/ Basic/Module.h • CocoaPods Source https://github.com/CocoaPods/CocoaPods/blob/master/lib/ cocoapods/generator/module_map.rb • Trial & Error Exploring Clang Modules – Samuel Giddins @ try! Swift Tokyo 2018 40
41. @segiddins Mobile Developer Experience @ Square Exploring Clang Modules 41